Method of manufacturing a closed impeller

Abstract

The application relates to the technical field of manufacturing of closed impellers, in particular to a manufacturing method of a closed impeller. The manufacturing method of the application realizes high-precision manufacturing of the closed impeller by process structure design on the to-be-welded blank of the wheel cover and the semi-open impeller, combined with a dynamic pre-tightening welding assembly positioning clamp, and further combined with an integral brazing and post-welding integral finishing step, effectively ensures control of the welding seam gap between the wheel cover and the semi-open impeller, overcomes the inconsistency problems of the welding seam size of each blade and the wheel cover in the same impeller and the inconsistency problems of the welding seam size between different impellers caused by objective welding conditions such as clamp assembly errors and pre-welding filler assembly differences, guarantees the consistency and stability of the welding quality of the closed impeller, and further guarantees the coaxiality of the wheel cover and the semi-open impeller after welding, ensures the post-welding dynamic balance performance of the closed impeller and the stability of the subsequent machining process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of closed impeller manufacturing process, in particular to a manufacturing method of closed impeller. BACKGROUND

[0002] The closed impeller is a commonly used impeller structure in centrifugal compressors, which has the technical advantages of small overflow loss and high compression efficiency compared with the open impeller, and can more efficiently compress gas and be used for the design and manufacture of high-pressure-ratio centrifugal compressors.

[0003] Due to the complex gas passage cavity between the internal blades of the closed impeller, it is difficult to directly manufacture by integral forming through casting process. At present, the main manufacturing method of the closed impeller in the related art is to form the semi-open impeller and the cover into one body by welding, wherein the welding process includes electric arc welding, laser welding and brazing. For the closed impeller with a flow channel outlet width of ≤15mm, due to the complex product flow channel structure, small outlet size and high manufacturing precision requirement, the electric arc welding, laser welding and other methods are used, and the welding position inside the flow channel has poor accessibility, and the welding seam between the blade and the cover of the complex structure of the closed impeller flow channel has certain welding blind spot problem, which cannot meet the manufacturing requirements of the product. Therefore, the brazing method is mainly used for manufacturing the closed impeller with a relatively narrow outlet width.

[0004] For the brazing technology, the brazing seam width and the size of the fillet formed by the filler metal are the decisive factors of the welding performance, and the brazing seam width size of the filler metal is mainly determined by the assembly gap between the workpiece welding surfaces during the welding process. Therefore, controlling the assembly gap between the workpiece welding surfaces during the welding process and the filler metal filling size is the key control technology to ensure the brazing quality. However, there are few records of effective and accurate control methods for the assembly gap size of the welding surface in the prior art. In the existing brazing process, since the gap between the welding surfaces (i.e. the assembly gap) is not accurately controlled, the workpiece is usually assembled in a zero-assembly manner before welding, and the welding surfaces of the workpiece are in close contact after assembly, without leaving a reasonable assembly gap to fill the filler metal. The connection of the welding joint is only realized by the fillet or the weld reinforcement formed by the filler metal filling, so that a reasonable brazing seam cannot be formed to ensure the welding strength.

[0005] The applicant's prior patent (publication number CN116372488B) discloses a welding assembly positioning fixture for a closed impeller, which controls the assembly gap between the wheel cover and the welding surface of the impeller by fixture design, and fastens the wheel cover, filler metal and impeller into an integral piece for overall heating and welding. In the patent method, due to the installation error between the pre-fabricated size of the filler metal before installation and the process of the installation process, there will be a certain deviation in the welding surface gap (assembly gap) size formed after the assembly of different blades of the same impeller and different impellers. On the other hand, the welding surface gap after assembly with the fixture with filler metal is usually larger than the reasonable weld width size. Therefore, when welding, the filler metal melts, and the weld formed by the filler metal filling often has problems such as lack of welding or incomplete filling of the weld, which affects the quality of the weld; and due to the inconsistency of the weld size, the coaxiality of the wheel cover and the impeller after welding is poor, which further causes the problem of poor dynamic balance performance of the impeller after welding. Therefore, it is necessary to design a process scheme that can control the assembly gap of the welding surface for the brazing of the closed impeller.

[0006] It should be noted that the information disclosed in this BACKGROUND section is only intended to deepen the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that this information constitutes prior art known to those skilled in the art. SUMMARY

[0007] Therefore, the purpose of the present application is to provide a manufacturing method for a closed impeller, which combines the blank structure size design of the welding parts and the dynamic pre-tightening welding assembly positioning fixture, can accurately control the assembly gap between the wheel cover and the semi-open impeller welding surface and the weld width size during brazing, realize high-quality welding between the wheel cover and the semi-open impeller during the brazing process of the closed impeller, and ensure the size accuracy and quality stability of the closed impeller manufacturing by combining the subsequent overall finishing process.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] The present application provides a manufacturing method for a closed impeller, comprising the following steps:

[0010] S1 Blank structure and size design of the welding part: on the basis of the size of the finished product of the closed impeller, the first machining allowance is extended along the shape of each blade of the semi-open impeller at the gas outlet end, and a process boss with a height consistent with the optimal weld width size is reserved in the normal direction of the welding surface of the blade extension segment;

[0011] S2 Dynamic pre-tightening assembly before welding: the filler metal is applied on the welding surface of each blade, the process boss is not pre-loaded with filler metal, and the semi-open impeller, the filler metal and the cover are assembled by a welding assembly positioning fixture; the welding assembly positioning fixture comprises a dynamic pre-tightening mechanism, which can dynamically adjust the assembly gap between the cover and the semi-open impeller along the installation axis direction of the semi-open impeller; wherein the filling thickness of the filler metal is slightly greater than the height of the process boss;

[0012] S3 Integral brazing: after the welding assembly positioning fixture is used to complete the integral assembly of the cover, the filler metal and the semi-open impeller before welding, the assembly is integrally brazed by brazing process;

[0013] S4 Overall finishing after welding: after brazing, the welding assembly positioning fixture is removed, and the obtained closed impeller welding assembly is overall finished to obtain a closed impeller product with qualified welding quality and size.

[0014] Further, the outlet flow channel width of the closed impeller is ≤15mm.

[0015] Further, the length dimension of the process boss along the radial direction of the blade is less than the first machining allowance by 0.3-0.5mm.

[0016] Further, the S1 further comprises the steps of reserving a second machining allowance in the thickness direction of the outer contour surface of the cover, and reserving a third machining allowance and a fourth machining allowance in the gas inlet port and the gas outlet port of the cover along the opening direction respectively; the S4 further comprises the steps of removing the thickness allowance of the cover along the outer contour surface of the cover and finishing the extension machining allowance of the gas inlet port and the gas outlet port of the cover.

[0017] Further, the first machining allowance is set to 2-3mm.

[0018] Further, the optimal weld width dimension is set to 0.1-0.2mm.

[0019] Further, the second machining allowance, the third machining allowance and the fourth machining allowance are respectively set to 1.5-2mm.

[0020] Further, the filling thickness of the filler metal exceeds the height of the process boss by 0.1-0.2mm.

[0021] Further, the welding assembly positioning fixture in S2 comprises:

[0022] The positioning mandrel comprises a positioning shaft segment and a limiting structure; the positioning shaft segment is coaxially matched with the center hole of the half-open impeller; the limiting structure limits the installation position of the half-open impeller in the axial direction;

[0023] The multi-claw positioning support comprises a second center hole and a contact matching surface; the second center hole is coaxially matched with the positioning shaft segment, and the multi-claw positioning support can slide up and down along the axial direction of the positioning mandrel; the contact matching surface is coaxially arranged with the second center hole and is in contact with the annular end of the wheel cover air inlet port; the center of the multi-claw positioning support forms an annular frustum;

[0024] The control handle and the dynamic pre-tightening mechanism; the end of the control handle is provided with an annular sleeve structure corresponding to the frustum, and an elastic member is sleeved between the frustum and the sleeve structure to guide the movement of the elastic member; the elastic member exerts force on the multi-claw positioning support, so that the contact matching surface always abuts against the inner or outer annular surface of the annular end.

[0025] Further, the brazing process is vacuum brazing or salt bath brazing.

[0026] The beneficial effects of the present application are:

[0027] The present application effectively realizes the control of the weld width size between the wheel cover and the half-open impeller by designing the process structure of the to-be-welded blank of the wheel cover and the half-open impeller and combining the dynamic pre-tightening welding assembly positioning clamp, overcomes the inconsistency of the welds of each blade in the same impeller and the inconsistency of the weld sizes between different impellers caused by objective welding conditions such as clamp assembly errors and pre-welding filler assembly differences, effectively ensures the consistency and stability of the closed impeller welding quality, and further ensures the coaxiality of the wheel cover and the half-open impeller after welding, ensures the post-weld dynamic balance performance of the closed impeller and the stability of the subsequent machining process; further, the closed impeller product with uniform welds and size precision meeting the requirements is obtained through overall finishing after welding. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 According to some embodiments of the present application, a process flow chart of a manufacturing method of a closed impeller is shown;

[0029] Figure 2 According to some embodiments of the present application, a structural schematic diagram of a welding assembly positioning clamp is shown;

[0030] Figure 3 According to some embodiments of the present application, a structural schematic diagram of a positioning mandrel is shown;

[0031] Figure 4 According to some embodiments of the present application, a structural diagram of a multi-prong positioning support is shown;

[0032] Figure 5 According to some embodiments of the present application, a structural diagram of a control handle is shown;

[0033] Figure 6 According to some embodiments of the present application, an assembly structural diagram of a closed impeller welded piece is shown;

[0034] Figure 7 According to some embodiments of the present application, a partial cross-sectional view of Figure 6 is shown;

[0035] Figure 8 According to some embodiments of the present application, a structural diagram of a semi-open impeller blank piece is shown;

[0036] Figure 9 According to some embodiments of the present application, a partial enlarged view of Figure 8 A portion is shown;

[0037] Figure 10 According to some embodiments of the present application, a partial enlarged view of Figure 8 B portion is shown;

[0038] Figure 11 According to some embodiments of the present application, a structural diagram of a wheel cover blank piece is shown;

[0039] Figure 12 According to some embodiments of the present application, a partial enlarged view of Figure 11 C portion is shown;

[0040] Figure 13 According to some embodiments of the present application, a partial enlarged view of Figure 12 D portion is shown;

[0041] Figure 14 According to some embodiments of the present application, structural diagrams of a semi-open impeller, a filler metal, and a wheel cover are shown;

[0042] Explanation of reference signs:

[0043] 100, semi-open impeller; 110, first center hole; 120, blade; 121, process boss; 122, extension section; 200, wheel cover; 210, air inlet end; 214, outer profile surface; 220, air outlet end; 300, brazing filler metal; 400, welding assembly positioning clamp; 410, positioning mandrel; 411, limiting structure; 412, positioning shaft section; 413, connecting section; 420, multi-prong positioning support; 421, second center hole; 422, positioning prong; 4221, prong structure; 4222, contact mating surface; 4223, finger structure; 423, circular table; 430, control handle; 431, mating portion; 432, sleeve structure; 433, connecting portion; 434, control portion; 440, spring. DETAILED DESCRIPTION

[0044] The technical features and advantages of the present application will be described in more detail below with reference to the accompanying drawings, so that the advantages and features of the present application can be more easily understood by those skilled in the art, and the scope of protection of the present application can be more clearly and definitely defined.

[0045] It should be noted that in the description of the present application, the terms indicating the direction or positional relationship of "up", "down", "left", "right", "inner", "outer" and the like are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0046] The terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implying the importance of the technical features shown.

[0047] In addition, it should also be noted that in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0048] The embodiment of the application provides a manufacturing method of a closed impeller, which is applied to obtain a closed impeller product by a whole brazing process+post-welding finishing of a semi-open impeller and a wheel cover, the process method is used for performing process structure design on a welding surface of the wheel cover and the semi-open impeller blank, and a dynamic pre-tightening welding assembly positioning clamp is combined, so that the consistency of the welding surface gap between each blade of the impeller and the wheel cover and the stability of the welding seam size between different closed impellers can be effectively ensured, the stability of the welding seam quality is ensured, and then the post-welding dynamic balance performance of the closed impeller and the stability of the subsequent machining process are ensured.

[0049] Please refer to Figure 1 The manufacturing method of the closed impeller of the embodiment of the application specifically comprises the following steps.

[0050] S1 Structure and size design of the blank: on the basis of the size of the closed impeller product, each blade of the semi-open impeller blank is extended along the radial direction by a first machining allowance, and a process boss with a height consistent with the optimal welding seam width size is reserved in the normal direction of the welding surface of the extended blade section at the gas outlet end.

[0051] S2 Dynamic pre-tightening assembly before welding: the semi-open impeller and the wheel cover blank are assembled through the welding assembly positioning clamp, and filler metal is filled between the welding surfaces of the semi-open impeller and the wheel cover, and the process boss is not pre-filled with filler metal; the welding assembly positioning clamp comprises a dynamic pre-tightening mechanism, the dynamic pre-tightening mechanism can dynamically adjust the assembly gap between the wheel cover and the semi-open impeller along the mounting shaft direction of the semi-open impeller, and ensures that the welding surface of the semi-open impeller, the welding surface of the wheel cover and the filler metal are always in close contact.

[0052] S3 Whole brazing: after the whole assembly before welding is completed, the whole brazing between the semi-open impeller and the wheel cover is performed by using a brazing process.

[0053] S4 Whole finishing after welding: after the brazing is completed, the welding assembly positioning clamp is removed, and the obtained closed impeller welding piece is subjected to whole finishing, so that the closed impeller product with qualified welding quality and size precision is obtained.

[0054] In the processing scheme of the embodiment of the present application, the first control factor is S1, the process structure and size design of the blank structure. The blade of the semi-open impeller is extended, and a process boss is designed on the extended surface to be welded. The height of the process boss controls the size of the weld width. The second control factor is S2, the dynamic pre-tightening clamping between the semi-open impeller, the filler metal and the cover. The dynamic pre-tightening mechanism makes the cover have a tendency to move towards the semi-open impeller during the melting of the filler metal, so that the surfaces to be welded of the semi-open impeller and the cover are always in close contact with the filler metal. Through the cooperation of the limiting of the height of the process boss and the dynamic clamping of the dynamic pre-tightening mechanism, a stable size of the weld gap is formed between the cover and the surfaces to be welded of each blade, the size of the brazing weld is accurately controlled, the high-quality welding between the cover and the semi-open impeller during the brazing of the closed impeller is realized, and the size accuracy of the closed impeller after welding is ensured while the good dynamic balance performance is ensured.

[0055] Before welding, the filler metal to be welded is pre-loaded between the surfaces to be welded of the cover and the semi-open impeller, and no filler metal is pre-loaded at the process boss. The surfaces to be welded of the cover, the filler metal and the surfaces to be welded of the semi-open impeller are connected into a whole through the clamping of the welding assembly positioning clamp, and the thickness of the pre-loaded filler metal is slightly greater than the optimal weld width to meet the weld filling requirement. Since the assembly gap of the surfaces to be welded after the assembly of the filler metal is greater than the optimal weld width, during the welding process, the dynamic pre-tightening mechanism of the clamp reduces the assembly gap between the surfaces to be welded of the semi-open impeller and the cover. With the reduction of the above-mentioned gap, the cover contacts the process boss on the semi-open impeller, the height of the process boss limits the axial displacement size of the semi-open impeller, so that the semi-open impeller and the cover stop moving after reaching the optimal assembly gap size between them, the assembly gap of the surfaces to be welded stops reducing, the molten filler metal fills the gap between the surfaces to be welded to form a weld of ideal size, and the welding process of the closed impeller is completed. On the one hand, the machining sizes of different blade pieces of the semi-open impeller blank structure can be kept consistent through the mechanical machining process, the consistency of the weld sizes between each blade of the same impeller is ensured through welding, the coaxiality deviation between the cover and the semi-open impeller due to the inconsistent weld width is avoided, and the dynamic balance performance of the closed impeller after welding is ensured. On the other hand, the inconsistency of the weld sizes between different impellers due to the assembly error of the clamp can be effectively overcome, the stability of the closed impeller welding quality is effectively ensured, and the stability of the subsequent machining process is ensured.

[0056] Further, in order to reserve machining allowance for the overall finishing step in S4, a second machining allowance is reserved in the thickness direction of the outer profile surface of the wheel cover blank; at the air inlet port and the air outlet port of the wheel cover blank, a third machining allowance and a fourth machining allowance are respectively reserved along the opening direction; in addition, a fifth machining allowance is reserved at the center hole of the semi-open impeller blank. After overall brazing is completed, the above machining allowances are removed through overall finishing, and the control of the size precision of the closed impeller finished product is realized through the finishing process.

[0057] In the embodiments of the present application, the specific design scheme of the welding assembly positioning clamp can refer to the prior patent CN116372488B of the applicant. Specifically, please refer to Figure 2 The welding assembly positioning clamp 400 includes a positioning mandrel 410, a multi-jaw positioning support 420, a control handle 430, and a dynamic pre-tightening mechanism (not shown in the figure).

[0058] Please refer to Figure 3 The positioning mandrel 410 includes a positioning shaft segment 412 for cooperating with the center hole of the semi-open impeller, a limiting structure 411 for limiting the installation position of the semi-open impeller in the axial direction, and a connecting segment 413 for connecting with the control handle 430. Among them, the positioning shaft segment 412 and the center hole of the semi-open impeller form coaxial cooperation, the limiting structure 411 can be designed as a stepped structure, and after the semi-open impeller is sleeved on the positioning shaft segment 412, it is seated on the upper part of the stepped structure, realizing the limiting in the axial direction.

[0059] Please refer to Figure 4As shown in FIG. 6, the structure of the multi-prong positioning support 420 is shown, which includes a second central hole 421 coaxially matched with the positioning shaft segment 412 of the positioning mandrel 410, and a contact matching surface 4222 matched with the annular end of the air inlet end of the wheel cover. The contact matching surface 4222 is coaxially arranged with the second central hole 421, and since the second central hole 421 is coaxial with the positioning mandrel 410, the contact matching surface 4222 always abuts the air inlet end of the wheel cover during the welding process, thereby ensuring the coaxial matching between the wheel cover and the semi-open impeller. The multi-prong positioning support 420 includes three positioning prongs 422 evenly distributed in the circumferential direction, each of which is spaced by 120°, and each of which includes a prong structure 4221 and a finger structure 4223 arranged at the end of the prong structure 4221. The finger structure 4223 is arranged approximately parallel to the positioning mandrel 410, and the contact matching surface 4222 is arranged on the finger structure 4223. The contact matching surfaces 4222 on the three positioning prongs 422 together form an annular surface coaxially arranged with the second central hole 421. Since the contact matching surface 4222 always abuts the air inlet end of the wheel cover, the air inlet end and the second central hole 421 always maintain coaxial matching, and the second central hole 421 is coaxial with the positioning shaft segment 412 and the central hole of the semi-open impeller, so that the wheel cover and the semi-open impeller can always maintain coaxial assembly before and after welding.

[0060] Please refer to Figure 5 As shown in FIG. 7, the structure of the control handle 430 is shown, which includes a matching part 431 matched with the positioning mandrel 410, a control part 434 for operating the clamp, and a connecting part 433 connecting the control part 434 and the matching part 431.

[0061] The dynamic pre-tightening mechanism is arranged between the control handle 430 and the multi-prong positioning support 420, and is used to form a dynamic pre-tightening force on the multi-prong positioning support 420. The pre-tightening force of the dynamic pre-tightening mechanism makes the wheel cover always abut the semi-open impeller. The contact matching surface 4222 of the multi-prong positioning support 420 guides and limits the downward displacement of the wheel cover, so that the wheel cover always maintains coaxial matching with the semi-open impeller during displacement. The dynamic pre-tightening mechanism can be a spring. The center of the multi-prong positioning support 420 forms an annular circular table 423, and the end of the control handle 430 corresponds to an annular sleeve structure 432, which is used as a spring sleeve between the circular table 423 and the sleeve structure 432 to guide the movement of the spring. Figures 6-7As shown in FIG. 6, the positioning core shaft 410 is connected with the control handle 430, and the spring 440 is supported between the control handle 430 and the multi-jaw positioning support 420 to provide elastic pre-tightening force to the multi-jaw positioning support 420, and the multi-jaw positioning support 420 applies force to the semi-open impeller 100 and the wheel cover 200 to achieve accurate positioning.

[0062] The positioning core shaft 410 and the control handle 430 are provided with a threaded cooperation structure. Specifically, the upper end of the positioning core shaft 410 is provided with an external thread structure 413, and the lower end of the control handle 430 is correspondingly provided with a threaded hole 431. After the semi-open impeller 100, the wheel cover 200, the multi-jaw positioning support 420, and the spring 440 are sequentially installed on the positioning core shaft 410, the control handle 430 is screwed into the external thread structure 413 of the positioning core shaft 410 to achieve assembly positioning. By rotating the control handle 430 through the control part 434, elastic pre-tightening can be achieved to clamp the semi-open impeller 100 and the wheel cover 200.

[0063] Please refer to FIG. 6 Figures 8-10 As shown in FIG. 7, in the process structure diagram for the semi-open impeller blank structure design in the embodiment, at the air outlet end, each blade 120 of the semi-open impeller 100 is outwardly extended by a first machining allowance RMA1 based on the finished product size. The size of the first machining allowance RMA1 can be set to be between 2-3 mm. At the same time, a process boss 121 with a height h consistent with the optimal weld width size is reserved on the normal direction of the welding surface of the extended segment 122 of the blade 120. The length l1 of the process boss 121 in the blade length direction is slightly smaller than the extended length of the blade 120, l1=1.7-2.5 mm. The purpose of setting l1 to be smaller than the length of the extended segment 122 of the blade is to achieve good welding with the wheel cover at the first machining allowance RMA1, to reserve a machining allowance for subsequent finishing, and to avoid affecting the weld quality at the air outlet port during the finishing process.

[0064] In addition, in order to ensure the assembly coaxiality between the welding assembly positioning clamp 400 and the semi-open impeller 100, the first center hole 110 of the semi-open impeller 100 and the center holes of the positioning core shaft 410 and the multi-jaw positioning support 420 are zero parts during assembly. Therefore, in order to ensure the dimensional accuracy of the center hole of the closed impeller after welding, a fifth machining allowance RMA5 is reserved at the first center hole 110 of the semi-open impeller 100. In the overall finishing step after welding, the above machining allowance is removed.

[0065] Please refer to FIG. 6 Figures 11-13As shown in the process structure diagram of the wheel cover blank in the embodiment, the outer profile surface 214 of the wheel cover 200 is provided with a second machining allowance RMA2 in the thickness direction, and the two ends (the inlet end 210 and the outlet end 220) of the wheel cover 200 are respectively provided with a third machining allowance RMA3 and a fourth machining allowance RMA4 in the outlet direction, wherein the second machining allowance RMA2 can be set to 1.5-2 mm, and the third machining allowance RMA3 and the fourth machining allowance RMA4 can be set to 1.5-2 mm. The above machining allowances are the machining allowances reserved for subsequent finishing, which can fully ensure that the size accuracy of the closed impeller product can be achieved after overall finishing.

[0066] Referring to Figure 14 Before brazing, the filler metal 300 is laid on each blade 120 of the semi-open impeller 100, and the filling thickness of the filler metal 300 is greater than the optimal weld width dimension (i.e., the height dimension h of the process boss 121) by 0.1-0.2 mm. The filler metal 300 is laid while avoiding the position of the process boss 121. Then, the wheel cover 200 is installed above the semi-open impeller 100 on which the filler metal 300 is laid, and the semi-open impeller 100, the filler metal 300 and the wheel cover 200 are assembled together by the welding assembly positioning clamp 400, and are pre-tightened together by the spring 440 with a dynamic pre-tightening action and the multi-jaw positioning support 420 with an axial positioning action. In the pre-tightening state, due to the existence of assembly errors, the laid filler metal 300 cannot completely adhere to the upper and lower surfaces to be welded, and the filler metal 300 and the upper and lower surfaces to be welded are in a non-completely sealed state. The clamped closed impeller assembly is placed in a welding temperature field, and under the heating action of the welding temperature field, the filler metal 300 melts. Through the pre-tightening force of the spring 440 and the assembly control of the multi-jaw positioning support 420, at this time, the wheel cover 200 will have a downward movement trend, and will stop until the inner surface (i.e., the upper surface to be welded) of the wheel cover 200 contacts the process boss 121. At this time, an ideal assembly gap is formed between the wheel cover 200 and the surfaces to be welded of the semi-open impeller 100. After welding is completed, after the temperature cools and the filler metal 300 solidifies, the welding assembly positioning clamp 400 and the welded closed impeller assembly are taken out, and a closed impeller welding piece with good weld uniformity and dynamic balance performance can be obtained. Subsequently, the welding assembly positioning clamp 400 is removed, and the closed impeller assembly welding piece is subjected to overall finishing: the thickness allowance (i.e., the second machining allowance RMA2) of the wheel cover 200 along the outer profile surface 214 of the wheel cover 200 is removed by finishing; the outer extension section 122 (i.e., the first machining allowance RMA1) of the blade 120 and the process boss 121 part are finished; the first center hole 110 (i.e., the first machining allowance RMA5) of the impeller 100 is finished; and the machining allowances (i.e., the third machining allowance RMA3 and the fourth machining allowance RMA4) of the inlet end 210 and the outlet end 220 of the wheel cover 200 are finished, so that a closed impeller finished product with high weld quality and size accuracy meeting product requirements can be obtained.

[0067] In addition, in the embodiment, the integral brazing process can be vacuum brazing or salt bath brazing; and the integral finishing process can be machine turning.

[0068] It is detected that the consistency of the weld size between the blades and the stability of the weld size of different impellers are better, and the dynamic balance performance of the closed impeller is good.

[0069] In the description of the present specification, the description of the terms "some embodiments", "some examples", "exemplarily", "example", "preferably", or "further" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0070] The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings of the present application, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method of manufacturing a closed impeller, which is applied to manufacture a closed impeller by preparing a semi-closed impeller and a wheel cover, characterized in that, The method comprises the following steps: S1 blank structure and size design of the welding part: on the basis of the size of the finished product of the closed impeller, for the blank of the semi-open impeller, at the air outlet end, the first machining allowance is extended along the shape of each blade, and a process boss with a height consistent with the optimal weld width size is reserved in the normal direction of the welding surface of the blade extension segment; The first machining allowance is set to 2-3mm; The optimal weld width size is set to 0.1-0.2mm; The length dimension of the process boss along the radial direction of the blade is less than the first machining allowance by 0.3-0.5mm; For the blank of the wheel cover, a second machining allowance is reserved in the thickness direction of the outer contour surface, and a third machining allowance and a fourth machining allowance are respectively reserved along the opening direction of the air inlet port and the air outlet port of the wheel cover; S2 dynamic pre-tightening assembly before welding: the filler metal is applied to the welding surface of the blade, the process boss is not pre-filled with filler metal, and the semi-open impeller, the filler metal, and the blank of the wheel cover are assembled through a welding assembly positioning clamp; the welding assembly positioning clamp comprises a dynamic pre-tightening mechanism, the dynamic pre-tightening mechanism can dynamically adjust the assembly gap between the wheel cover and the semi-open impeller along the installation axis direction of the semi-open impeller; wherein the filling thickness of the filler metal is greater than the height of the process boss; The filling thickness of the filler metal exceeds the height of the process boss by 0.1-0.2mm; S3 integral brazing: after the welding assembly positioning clamp is used to complete the integral assembly of the wheel cover, the filler metal, and the semi-open impeller before welding, the assembly is subjected to integral brazing by using a brazing process; S4 integral finishing after welding: after brazing is completed, the welding assembly positioning clamp is removed, and the obtained closed impeller welding part is subjected to integral finishing, the outer contour surface of the wheel cover is finished to remove the second machining allowance, and the air inlet port and the air outlet port of the wheel cover are finished to remove the third and fourth machining allowances; a closed impeller finished product with uniform and consistent weld size and meeting the dimensional accuracy requirements is obtained; The second machining allowance, the third machining allowance, and the fourth machining allowance are respectively set to 1.5-2mm.

2. The method of manufacturing a shrouded impeller according to claim 1, wherein The outlet flow channel width of the closed impeller is ≤15mm.

3. The method of manufacturing a shrouded impeller according to claim 1, wherein The welding assembly positioning clamp in S2 comprises: A positioning mandrel comprising a positioning shaft segment and a limiting structure; the positioning shaft segment is coaxially matched with the center hole of the semi-open impeller, and the limiting structure limits the installation position of the semi-open impeller in the axial direction; A multi-claw positioning support comprising a second center hole and a contact fitting surface; the second center hole is coaxially matched with the positioning shaft segment, and the multi-claw positioning support can slide up and down along the axial direction of the positioning mandrel; the contact fitting surface is coaxially arranged with the second center hole and is in contact with the annular end of the air inlet port of the wheel cover; the center of the multi-claw positioning support forms an annular circular truncated cone; A control handle; and, The dynamic pre-tightening mechanism comprises an elastic member, the end of the control handle is provided with a ring-shaped sleeve structure corresponding to the circular table, the elastic member is sleeved between the circular table and the sleeve structure, and the movement of the elastic member is guided; the elastic member applies force to the multi-claw positioning support, so that the contact fitting surface always abuts against the inner side ring surface or the outer side ring surface of the ring-shaped end.

4. The method of manufacturing a shrouded impeller as defined in claim 1, wherein The brazing process is vacuum brazing or salt bath brazing.

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